1. Field
The present invention generally relates to synthesis of circuits and more specifically to synthesis of circuits that can operate at multiple frequencies and voltage levels.
2. Description of Related Art
Design of integrated circuits can involve using automated synthesis tools for determining a design and placement of circuitry to implement functions specified by a functional specification. Often, a synthesis tool will use building blocks, such as certain pre-defined logic assemblies, that have been characterized and are contained in a library. In many cases, such a library has been designed in view of certain process parameters, such as minimum feature size.
It is known that circuits and portions of circuits are designed with the expectation that they perform at certain clock rates, or otherwise can produce an output within a required time of receiving a triggering input. As such, circuits are synthesized and modified toward the view of meeting such timing requirements across a functional block being synthesized, or some other portion of a circuit, a circuit, or a chip, etc.
Power consumption of electronics has become an important issue. One way to reduce power consumption of a circuit is to reduce its operating voltage. However, it is generally true that a given circuit operates more slowly as its voltage is lowered (if it works at all). Slower operation usually correlates to lower performance. Thus, it is frequently a goal of integrated circuit design to be able to design circuits that can operate across a variety of voltage levels, which can be varied during operation such that an appropriate voltage setting can be selected for a level of performance. Circuit designs (e.g., for programmable or dedicated processors) that can select an operating frequency and voltage pair from among a number of frequency/voltage operating pairs may be described as Dynamic Voltage Frequency Scaling (DVFS) designs.
Improved methods for setting constraints during synthesis of DVFS designs is desirable.